This invention relates to yellow colorants comprising a chromophore having at least one poly(oxy-C2-C4-alkylene) chain attached to an aromatic methine backbone having at least one cyanoester moiety attached thereto. The ester portion must include a C1-C8 (such as ethyl, butyl, hexyl, or ethyl-hexyl) pendant group and the poly(oxyalkylene) chain must average at most 6 monomers and at least 3 monomers, with ethylene oxide as the capping group. Such a specific group of coloring agents provides the best overall yellow colorations or effects (either alone or in blends with other coloring agents, particularly at low color loadings) as well as the best overall low extraction levels when present within clear polyester (such as polyethylene terephthalate, for example), when compared to all other known polymeric yellow colorants for the same end-use. Compositions and articles comprising such colorants are provided as well as methods for producing such inventive colorants.
All U.S. patents cited within this specification are hereby incorporated by reference. There continues to be a need to provide versatile colorants within various applications such that the coloring agent itself exhibits excellent colorations (particularly at low color loadings and due to high color values due to low degrees of pendant group additions thereto and thus greater amounts of chromophore constituents within the colorant compound itself), high thermal stability, effective lightfastness (or drastic reduction in possibility of removal therefrom via extraction by solvents or like sources), ease in handling, ability to mix thoroughly with other coloring agents and thus to provide effective different hues and tints within or on target substrates, and acceptable toxicity levels. There has been a need to provide improved colorants meeting this criteria for certain thermoplastic media, such as polyesters, such that the colorants themselves exhibit excellent compatibility therein (for instance in terms of intrinsic viscosity loss and the other characteristics desired for such plastics as noted above). In particular, such characteristics for polyesters are desired for colorants that impart, for example, but not necessarily, a yellow shade to the target resin. It is believed and, as noted above, has been determined that such desirable polyester plastic colorations with the characteristics noted above are possible through the addition of certain pendant groups to the chromophore backbone which do not act as couplers or color modifiers and thus any chromophore (and resultant hue or tint) may be utilized.
Previous coloring agents for such end-uses have included pigments, dyes, or dyestuffs, with each having its own drawback. For instance, such pigments, dyes, and/or dyestuffs have not been widely introduced as colorants within plastics (such as polyolefins, polyurethanes, and the like) due to such physical limitations. However, the utilization of such colorants is highly desired for a number of reasons, foremost the actual colorations available from such specific compounds.
The standard types of polymeric colorants now utilized within plastics (be they thermoplastics or thermoset types) are primarily higher molecular weight poly(oxyalkylenated) compounds, such as methines, and the like (i.e., those found within U.S. Pat. No. 4,992,204, to Kluger et al.). Some of these colorants exhibit certain problems in associated with the high color loading required to obtain significant color strengths within certain thermoplastics, such as polyesters, as one important example. Such high color loadings have a detrimental impact on the intrinsic viscosity of the target polyester (such as polyethylene terephthalate) which can effectively deleteriously have a direct impact on the strength of the target plastic itself. Thus, colorants are needed that do not exhibit such problematic effects on polyesters while still permitting thorough and substantially uniform colorations throughout the target polyester (as one thermoplastic example). Other chromophores cannot be utilized (such as triphenylmethanes, and certain azos) due to their lack of sufficient thermal stability to retain colorability when exposed to processing conditions associated with thermoplastic (e.g., primarily polyester) production. Thus, there is a need to select proper chromophores to provide yellow colorations as well as proper poly(oxyalkylene) chains and monomers in order to provide proper yellow poly(oxyalkylenated) colorants for utilization within thermoplastic (again, primarily, but not solely, polyester) formulations and articles. To date, only the higher molecular weight, and thus low color strength and/or thermally unstable, poly(oxyalkylenated) colorants have been taught within the prior art. Other colorants of either like high molecular weight or non-polymeric types have also been taught but suffer from a number of drawbacks (such as toxicity, lightfastness, thermal stability, ease in handling, and the like). There is thus a desire to introduce new types of colorants that meet these required characteristics and thus exhibit needed versatility with excellent coloring ability within desired end-uses, such as, without limitation, thermoplastics and thermosets. To date, although some liquid colorants (other than less-than-reliable pigment dispersions) have been developed for such target end-uses, unfortunately, as noted above, they have also exhibited certain limitations. A new liquid yellow colorant that provides effective colorations for such myriad end-uses as noted above and that exhibits excellent colorations, lightfastness, thermal stability, mixing with other coloring agents, and low toxicity, at least, is thus highly desired. Again, to date, there have been no teachings or fair suggestions of such a highly desirable, specific potentially liquid yellow colorant within the pertinent prior art or within the colorant industry itself.
It has thus now been determined that the attachment to a specific cyanoester methine compound of specific poly(oxy-C2-C4-alkylene) chains averaging at least 3 monomeric units and at most 6 monomeric units provides the needed and highly desired performance requirements noted above, particularly for transparent polyester formulations and articles. It is thus an object of the invention to provide such a colorant exhibiting (at least) excellent colorations (at low color loadings and thus causing minimal effects on intrinsic viscosity), low extraction levels, thermal stability, and lightfastness within target polyester articles (although such a specific liquid yellow colorant may be introduced within any number of thermoplastic and/or thermoset systems and/or articles). Another object of this invention to provide a yellow polymeric colorant exhibiting poly(oxyalkylene) groups that is easy to process, mixes well within target plastics, and provides excellent colorations at low color loadings within the target finished articles. Yet another object of this invention is to provide excellent colorations within liquid compositions (such as inks, and the like) through the utilization of such yellow liquid cyanoester-methine-based polymeric colorants, as noted above.
It is to be understood that the term alkyl as used throughout in relation to the ester portion of the cyanoester moiety on the methine backbone is intended to encompass any straight or branched alkyl moiety, having from 2 to 8 carbon atoms total, preferably, though not necessarily, an even number of carbon atoms within that range; the term poly(oxyalkylene) or alkyleneoxy, unless more specifically defined herein, is intended to encompass either oxyethylene, oxypropylene, or oxybutylene, with oxyethylene and oxypropylene preferred. It should be well understood by the ordinarily skilled artisan within the polymeric colorant field that an exact number of oxyalkylene monomers is rather difficult to attach and thus an average number is a more appropriate manner of describing such colorants in terms of poly(oxyalkylene) chain lengths. Although such an average is more proper as a description, it is still preferable, if possible, to attach a narrow distribution of different numbers of monomers (e.g., with an average of 5, most compounds will preferably exhibit at most 6 and at least 3 monomers) to the target chromophore. Therefore, the description of at most 6 monomers and at least 3 monomers is also preferable for specific embodiments, rather than averaging at most 6 monomers and at least 3 monomers.
The present invention preferably encompasses liquid, waxy, or pasty (at room temperature and standard pressure) colorants conforming to the structure of Formula (I) 
wherein R1, R2, R3, and R4 are the same or different and are selected from the group consisting of C1-20 alkyl, halo, hydroxyl, hydrogen, cyano, sulfonyl, sulfo, sulfato, aryl, nitro, carboxyl, and C1-20 alkoxy; Rxe2x80x2 is C1-C8 alkyl (either branched or unbranched if above three carbon atoms in length); and R is [(EO)w(PO)x(BO)y(EO)z]xe2x80x94H, wherein EO connotes ethyleneoxy, PO connotes propyleneoxy, BO connotes butyleneoxy, w is 1, x is 0-3, y is 0-3, and z is 2-6, wherein 3 less than w+x+y+z less than 6. Block copolymers are not required as mixed copolymers also function properly.
Compositions comprising such compounds of (I) are also encompassed within this invention, particularly those comprising such compounds and bluing agents, as liquids or as pellets for further introduction within desired molten thermoplastic formulations. Methods of making such compositions, particularly thermoplastics, comprising such compounds of (1) are also contemplated within this invention.
The term xe2x80x9cthermoplasticxe2x80x9d is intended to encompass any synthetic polymeric material that exhibits a modification in physical state from solid to liquid upon exposure to sufficiently high temperatures. Most notable of the preferred thermoplastic types of materials are polyolefins (i.e., polypropylene, polyethylene, and the like), polyester (i.e., polyethylene terephthalate, and the like), polyamides (i.e., nylon-1,1, nylon-1,2, nylon-6 or nylon-6,6), polystyrenes, polyurethanes, polycarbonates, polyvinyl halides (i.e., polyvinyl chloride and polyvinvyl difluoride, as merely examples), and the like. Preferred thermoplastics within this invention are polyesters and polyolefins, and most preferred is polyethylene terephthalate.
Such thermoplastic articles include bottles, storage containers, sheets, films, fibers, plaques, hoses, tubes, syringes, and the like. Included within this list would be polyester, polystyrene and other like resinous materials in sheet form which are present within windows for strength and resiliency functions. In such an instance, the inventive colorant compounds would provide or contribute to excellent colorations to such thermoplastic articles for decorative, aesthetic, and/or protective (such as ultraviolet or infrared protection) purposes. Basically, the possible uses for such a low-migratory, thermally stable colorant for such items as thermoplastics (particularly polyesters such as transparent polyethylene terephthalate) is voluminous and cannot easily be enveloped. Other possible end-uses, however, would include within solvent systems, printing inks, within and on textiles (either on or within textiles, fibers, or fabrics) and the like.
Other types of articles contemplated within this invention for the inventive colorant compounds include, again without limitation, thermoplastic articles, such as films, sheets, bottles, containers, vials, and the like, as well as thermosets (e.g., formulations that become solid in nature upon exposure to sufficient heat or amount of catalyst), such as polyurethanes, and the like, including, without limitation, though preferably, polyurethane foams. Other colorants may be added to or incorporated therein with such inventive colorant compounds to produce different hues and tints, again for aesthetic, decorative, and/or protective purposes. Ultraviolet absorbers may also be introduced, incorporated, and the like, in order to protect the article or, if in container for, the contents therein. In concert with certain embodiments of the inventive colorant, or combinations of colorants with certain inventive colorant embodiments, such UV absorbers may be added in reduced amounts, potentially, due to the protective abilities of the colorant or combination thereof in terms of reducing ultraviolet transmission (or inversely increasing ultraviolet absorptions).
Such thermoplastic colorants (and other additives) are typically added to such compositions during the injection molding (or other type of molding, such as blow molding), thereof, including, and without limitation, by mixing the liquid absorber with resin pellets and melting the entire coated pellets, or through a masterbatch melting step while the resin and absorber are pre-mixed and incorporated together in pellet form. Such plastics include, again without limitation, polyolefins, polyesters, polyamides, polyurethanes, polycarbonates, and other well known resins, such as those disclosed within U.S. Pat. No. 4,640,690, to Baumgartner et al., and U.S. Pat. No. 4,507,407, to Kluger et al. under the term xe2x80x9cthermoplasticsxe2x80x9d. Generally, such plastics, including the colorant, UV absorber, and other potential additives, are formed through any number of various extrusion, etc., techniques, such as those disclosed in the aforementioned U.S. patents. Preferred thermoplastics are polyesters, such as, in one non-limiting embodiment, polyethylene terephthalate. xe2x80x9cPlastic packagingxe2x80x9d thus encompasses containers, sheets, blister packages, and the like, utilized for storage purposes and which include the plastics in any combination as noted above.
The term xe2x80x9cpure, undiluted statexe2x80x9d as used in conjunction with the inventive colorant compounds indicates that the compounds themselves without any additives are liquid at room temperature or are flowable (viscosity of at most 60,000 cps) when heated to 40xc2x0 C. Thus, there is no need to add solvents, viscosity modifiers, and other like additives to the compounds to effectuate such a desirable physical state.
The presence of surfactants, solvents, and the like, may be utilized to alter the solubility, coloring characteristics, and the like, of the ultimate inventive polymeric methine colorant which would be understood and appreciated by the ordinarily skilled artisan within this particular art
The colorant compound (I), above, is, again, liquid in nature at ambient temperature and pressure and at substantial purity; however, pasty or waxy colorants are also encompassed within this invention, due to their handling improvement over clearly solid colorants of similar structures. In order to effectuate coloring of substrates and media, any other standard colorant additives, such as resins, preservatives, surfactants, solvents, antistatic compounds, antimicrobial agents, and the like, may also be utilized within the inventive colorant compound compositions or methods.
The inventive colorant compounds may be added in any amount to such thermoplastics up to their saturation limits therein. Preferably, the amount is between about 0.00001 ppm to about 25,000 ppm per total amount of resin; more preferably from about 0.001 to about 15,000 ppm; still more preferably from about 0.1 to about 5,000 ppm; and most preferably from about 100 to about 2,500 ppm. Of course, the more colorant present, the darker the shade therein. When mixed with other colorants within the target thermoplastic, the same amounts would be preferred with the saturation limit dependent upon the amount of any extra colorants therein.
The specific formulations below, as well as the following exemplified methods of producing such and methods of coloring using such are thus indicative of the preferred embodiments of this invention (as noted above, the number of oxyalkylene monomers are actually average numbers):